Various embodiments described herein relate to image sensors, and in particular, to transfer gates of image sensors.
An image sensor is a device that converts optical images into electrical signals. With increased development of the computer and communications industries, there is an increased demand for high performance image sensors in a variety of applications such as digital cameras, camcorders, personal communication systems, gaming machines, security cameras, micro-cameras for medical applications, and/or robots.
The image sensors may be generally classified into charge coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) image sensors. The CMOS image sensors may be operated using a simple operation method and may be configured to have signal processing circuits integrated on a single chip, and thus, the use of the CMOS image sensors makes it possible to realize scaled products. In addition, the CMOS image sensors can operate with relatively low consumption power, and thus, they are applicable to a product with low battery capacity (e.g., portable electronic devices). Furthermore, the CMOS image sensors may be fabricated using CMOS fabrication techniques, which may reduce manufacturing costs. Moreover, the use of the CMOS image sensors may provide images with high resolution, and thus, the demand for the CMOS image sensors is being increased.
A CMOS image sensor may include a photoelectric conversion region, a transfer gate and a floating diffusion region. When a voltage is applied to the transfer gate, charges generated in the photoelectric conversion region are transferred into the floating diffusion region.